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Evaporation Source

IP.com Disclosure Number: IPCOM000077488D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

van der Meulen, YJ: AUTHOR

Abstract

An evaporation source is described which consists of a tube having a suspended bottom for supporting a solid evaporant.

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Evaporation Source

An evaporation source is described which consists of a tube having a suspended bottom for supporting a solid evaporant.

The evaporation source is depicted in the figure and consists of a tube 2, which has a suspended bottom 4 and a removable cap 6 on one end. Current leads 8 and 10 are welded, respectively, to both ends of the tube and connect it with a power supply, not shown. The cap is machined to closely fit the tube and has a hole 12 in its center. By an appropriate choice of the length and the diameter of this central hole, various evaporant distributions can be effected. The diameter of the hole 12 should be much smaller than the diameter of the main tube. A thermocouple 14 is welded onto the tube. Prior to operation, the source is filled to approximately 50 volume per cent.

During operation the source is heated by passing current between 8,and 10, and a solid-vapor equilibrium is established inside the tube. The granular load has a small electrical conductivity and will not act as an electrical short. Tube and contents can thus be heated very evenly without use of radiative heat transfer. This makes the source very suitable for operation at temperatures ranging from 200 degrees C to 600 degrees C. The cross section of each of the leads 8 and 10 is roughly matched with that of the tube to effect a comparable temperature rise in both. It has been found that condensation of the evaporant in the exit opening 12 and between the cap and the m...